1. Field of the Invention
The present invention relates to a shutter device.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2008-180815 discusses an imaging apparatus that uses a focal plane shutter and an electronic shutter in combination with each other to execute an imaging operation. The conventional imaging apparatus starts an exposure operation by using an electronic shutter function of an image sensor. In addition, the conventional imaging apparatus controls a blade group constituted by a mechanical shutter to end an exposure operation.
In the above-described conventional imaging apparatus, after locking a drive lever by energizing an electromagnet, a set lever starts driving a mirror in a mirror-up direction. After the mirror-up operation, a blade lever is unlocked and an aperture formed by a blade group is opened. Subsequently, when the energization of the electromagnet is discontinued at a predetermined timing, the drive lever and the blade lever are driven simultaneously in a direction of closing the aperture.
In the focal plane shutter discussed in Japanese Patent Application Laid-Open No. 2008-180815, when the blade lever is unlocked to open the aperture by the blade group, the blade lever collides with the locked drive lever when the electromagnet is energized.
When the drive lever is locked by energizing the electromagnet, the drive lever is locked by attracting an armature with a yoke. If the blade lever collides with the drive lever in this state, attraction surfaces of the yoke and the armature may be damaged. If the attraction surfaces of the yoke and the armature are damaged, the attracting performance and the separation performance may degrade. As a result, the accuracy of the operation of the shutter device may degrade.
Alternatively, the drive lever and the blade lever may be driven by a mutually integrated operation after the drive lever has collided with the blade lever during the travel of shutter blades in the direction of closing an aperture. In this case, however, the pivot speed of the drive lever may vary due to the impact from the collision. As a result, the speed of travel of the shutter blades may vary. In this case also, the accuracy of the operation of the shutter device may degrade.